Ruegg



Oct. 3, 1950 EGG 2,524,637

R. RU MULTIPLE TUBE GAS HEATING FURNACE WITH MOVABLE TUBE SUSPENSIONMEANS Filed Sept. 4, 1946 2 Sheets-Sheet 1 Inuenior Rudolf Rue g 9Ai'iornegs Oct. 3, 1950 Filed Sept. 4, 1946 R. RUEGG 2,524,637 MULTIPLETUBE GAS HEATING FURNACE WITH MOVABLE TUBE SUSPENSION MEANS 2Sheets-Sheet 2 Invenkor Rudolf Ruegg bg 9Z Aitarneg s patented Oct. 3,1956 UNITED STATES P TENT OFFICE MEAN S Rudolf Ruegg, Zurich,Switzerland, assignor to Aktiengeseilschaft Fuer Technische Studien,Zurich, Switzerland, a corporation of Switzer land Application September4, 1946, Serial No. 694,703

1 In Switzerland September 26, 1945 Claims. (01. 126-109) chamber, thereis risk that flue gases may escape through said clearances into thesurrounding space, which, under certain circumstances may lead to injuryto the health of the workpeople in a short time. If on'the other handair is to be used.

a pressure below atmospheric should exist in the space filled withfurnace and flue gases, air can pass into this chamber through the saidclearances from outside, whereby as is well known the degree ofefiiciency of gas heaters is very greatly reduced. The provision ofpackings in such cases ismostly not possible for the reason thatstuifing boxes entail objectionable friction and bellows used to producepackless joints require too much space.

The object of the present invention is to provide a gas heater of thekind hereinbefore referred to in which, in connection with thesuspension of the tubes, packings can be dispensed with and the abovementioned disadvantages do not ,occur notwithstanding. For this purposewe provide, between those parts of the heater which are filled with fluegases and a chamber which contains the suspension device for the heatertubes and which is traversed by air serving to cool this device, afurther chamber, from which any flue gases which may pass into it andalso any air which may tend to pass into said chamher and thus into thepath of the flue gases, are

drawn off.

The accompanying drawings show by way of example and in a simplifiedmode of representation two embodiments of the subject matter of theinvention. In these drawings in which like reference numerals are usedto indicate similar parts: 7

Fig. 1 is a view of a gas heater chiefly in vertical axial section, butwith parts shown in elevation.

Fig. 2 shows a modification of a detail.

In the figures, i denotes the furnace chamber of an air heater and 2denotes those parts of the heater which are filled with flue gases. Theheater contains a large number of tubes 3 bent into the shape of a U,and suspended outside the furnace chamber movably at the top in a mannerto'be more fully described hereinafter. The air to be heated flows inthrough pipes 4 4 arranged parallel with each other, into twodistributors 5 and 6 respectively which are arranged at the bottom ofthe heater. Some of the tubes 3 are connected to the distributor 5 andthe remainder of them to the distributor t, and all these tubes 3 arealso connected to a common header l for the air heated in these tubes 3.Said header l is likewise arranged at the'bottom of the heater. The airthen passes intoa pipe 8 to the place (not shown) where such hot In thetype of construction herein described-the longitudinal expansion of thetwo substantially parallel branches of the U-shaped tubes 3 ispractically equalised. The distributors 5, 6 and the header 1 are nottherefore subjected to any movements in a vertical direction andconsequently only expansions'in a horizontal direction have to be takeninto account, which, regarded from a constructive standpoint, is to bevalued as a great advantage. Owing to the arrangement of thedistributors 5, 6 and of the header l at the bottom ofthe heater thetubes '3 must be suspended movably at the top and the suspending meansmust 'be yieldably supported. For this purpose we provide in conjunctionwith each tube 3 a suspension rod ill and a spring H which tends to drawsaid rod upwards. The various springs H are supported by a plate l2,which counterweights l3 tend to draw upwards. The rods 10 are passedwith clearance through the cover [4 of the heater which consists atleast in part of some heat insulating material. Above the parts 2 of theheater which are filled with flue gases, are arranged two plates I5, itthrough which all the tubes 3 suspended by the rods 10 are passed withclearance. These plates lii, [6 enclose a space II which is connecedby apipe 53 to a pipe 19. Through this latter a 'fan 20 draws flue gases ofifrom-the lower part of the heater and delivers them again into thefurnace chamber l through a pipe 2i at the top 'for cooling purposes.The greater part of the suspension and counterbalancing device til, ii,t2, '"I'3 for the heater tubes 3 is housed in a chamber 23 closed at thetop and sides by a box-like casing 22 and at the bottom by the cover it.Fresh air under pressure is delivered to this chamber 23 by a fan 24 forcooling purposes, and after leaving the chamber '23 said air is heatedup further in a heat exchanger 25 by waste gases, after which it flowsthrough a pipe 25 to the burner 26 as air for the support of combustion.Fuel flows also to the burner 28'through a pipe '21.

In the type of construction described a pressure above atmosphericexists in the chamber 23 filled with fresh air, and in the parts 2 whichare filled with flue gases, exists according as the plant is a normalone with an exhaust fan or has a charged combustion chamber, either aslight pressure below atmospheric pressure or a pressure aboveatmospheric pressure, the latter being however smaller than that whichexists in the chamber 23. Notwithstanding the movable suspension of thetubes 3 no fresh air under pressure can pass out of the chamber 23 tothe parts 2, because any air which might pass through the clearance inthe cover 14 and in the upper plate I6 into the space I! will beexhausted from said space I! by the fan before it can pass through theclearances in the plate IE to the parts 2.

If a pressure above atmosphereic and greater than that in the chamber 23exists at the parts 2, no flue gases can escape into the surroundingneighborhood, because the fiue gases which get as far as the exhaustspace i? are drawn off therefrom by the fan 23, so that they cannot geteven into the space between the plate l6 and the cover l4.

As shown in Fig. 2, in some circumstances a single plate 28 between theparts 2 which are filled with fiue gases, and the cover It, will besufiicient. In such case the exhaust space 29 bebetween the plate 28 andthe cover Id must be connected up to the fan 20. When this is done it isadvisable to make the partition it between the exhaust space 2% and thechamber 23 which contains the suspension and equalising device ll, l2,l3 for the heater tubes and through which the suspension rods ill forthe heater tubes 3 are passed, likewise at least partially of heatinsulating material.

What is claimed is:

1. The combination of means enclosing a combustion chamber, at least onewall of said enclosing means being provided with a plurality ofapertures for the passage of corresponding tubesuspending means; aburner for causing combustion of fuel in said combustion chamber;yielding tube-suspending means external to said enclosing means,associated with said apertured wall, and having tube-engaging extensionswhich pass and are movable longitudinally through respective apertures;a housing enclosing said tube-suspending means; means for circulating agaseous cooling medium through said housing; at least one partitiondisposed within said enclosing means and defining therein a combustionchamber proper and an intervening chamber between said wall and saidpartition, said partition also being provided with a plurality ofapertures,- the disposition of the apertures in said partition being afunction of the disposition of the apertures in said wall; a pluralityof tubes having straight portions which extend through the apertures insaid partition and are formed with bent portions which engage saidtube-engaging extensions within said intervening chamber, each tube andeach tube-engaging extension nearly filling the aperture through whichit passes; and circulating means operatively connected to saidintervening chamber and to said combustion chamber to withdraw gasesdirectly from said intervening chamber and deliver them to saidoombustion chamber at a rate such as to maintain in the interveningchamber a pressure which is" lower than the lowest pressur concurrentlyexisting in the combustion chamber and in said housing.

2. The combination defined in claim 1 in which the straight portions ofthe tubes are substantially vertical and are suspended at their upperends from said tube-engaging extensions.

3. The combination defined in claim 1 in which the tubes have parallelvertical straight portions connected within said intervening chamber bya bend, forming an inverted U, and said tube-engaging extensions engagerespective bends.

4. The combination defined in claim 1 in which the tubes have parallelvertical straight portions connected within said intervening chamber bya bend, forming an inverted U, and said tube-engaging extensions engagethe bend, and the lower ends of said straight portions are connected tofixed manifolds.

5. The combination defined in claim 1 in which there are two similarlyapertured partitions spaced apart and both traversed by the tubes;namely, a first partition adjacent the combustion chamber, and a secondpartition between the first partition and the apertured wall; and thecirculating means is operatively connected to the space between thefirst and second partitions so as to draw gases directly from said spaceand indirectly from the space between the second partition and theapertured wall, in which space the tube-engaging extensions engage thetubes.

6. A gas heater comprising in combination means enclosing a combustionchamber and an ofitake passage for products of combustion leading fromsaid chamber, one wall of said enclosing means having a plurality ofspaced apertures for the passage of corresponding tube-suspending means;a burner arranged to cause combustion of fuel within said chamber; aplurality of yielding suspending means supported outside said combustionchamber and each having tubeengaging extensions which pass and aremovable longitudinally through corresponding ones of said apertures; ahousing enclosing said yielding suspending means; means for circulatinga gaseous cooling medium through said housing; at least one partitioninterposed between the interior of the combustion chamber and saidapertured wall and serving to define between said wall and partition anintervening chamber, said partition also being provided with a pluralityof apertures, the disposition of the apertures in said partition being afunction of the disposition of the apertures in said wall; tubesarranged for the passage therethrough of gas to be heated, said tubesbeing so located within the combustion chamber as to be swept bycombustion and flue gases flowing from said burner to said off-takepassage, said tubes passing through apertures in said partition, andentering within said intervening chamber into engagement with saidtube-engaging extensions; and circulating means operatively connectedto'said intervening chamber and to said combustion chamber so as towithdraw both flue gases and cooling medium from said interveningchamber and for discharging the same into said combustion chamber.

7. The combination defined in claim 6 in which the tubes are vertical,the apertured wall of the combustion chamber is at the top and the tubeshave fixed connections at their lower ends.

8. The combination defined in claim 6 in which the tubes are vertical,the apertured Wall of the combustion chamber is at the top, the tubeshave fixed connections at their lower ends, and said yielding suspendingmeans comprise suspender 5 rods which serve as the tube-engagingextensions, a counter-Weighted platform and a plurality of springs onereacting between the platform and each of said rods.

6 V gases from the intervening chamber includes an inlet connectionleading from the ofitake, Whereby the circulating means delivers a,mixture of flue gases and cooling medium to said combustion 9. Thecombination defined in claim 6 in which 5 chamber.

RUDOLF RUEGG;

REFERENCES CITED The following references are of record in the 10 fileof this patent:

UNITED STATES PATENTS Name Date Keller l -l Dec. 10, 1940 Number

